JPH10164537A - Video communication system, information processing apparatus, and control method therefor - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make it possible to reduce a difference between a time obtained by a video transmitting terminal and a time at which a video displaying terminal displays a video at the time of remote operation of an imaging device. A video camera provided in a communication terminal.
When the video information from 2 is received, the received video information is buffered by the video buffer unit 27, and an image is displayed on the display 22 based on the video information stored in the video buffer unit 27. Camera control detector 2
5, when the video camera 12 detects that the video camera 12 is in the controlled state, the fact is transmitted to the buffer suppression unit 26. The buffer suppression unit 26 inhibits the buffering of the video buffer unit 27 while the video camera 12 is in the controlled state, and causes the display 22 to immediately display the received video information.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a video communication system capable of remotely controlling an imaging device, an information processing device, and a control method thereof.

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing an outline of a general video communication system. FIG. 9 is a block diagram showing a schematic configuration of a general video communication system. For example, the communication terminal 100 as a video server that controls the camera and transmits the video is, as shown in FIG.
01, a keyboard 102, a mouse 103, a display 104, and a video camera 105. As shown in FIG. 8, a communication terminal 200 as a video client that receives video data from the communication terminal 100 and displays the video data includes a computer main body 201 and a keyboard 20.
2, a mouse 203 and a display 204 are provided. Then, the communication terminal 100 and the communication terminal 200
00 is communicatively connected.

[0003] As shown in FIG. 9, an image captured by a video camera 105 of a communication terminal 100 is input to an image input unit 1.
Digitized by 10. Then, the digitized video data for one screen is transmitted to the network transmitting / receiving unit 11.
1 and output on the network 300. The packet output on the network 300 is received by the network transmission / reception unit 211 of the communication terminal 200. When receiving the packet, the communication terminal 200 converts the received packet into data and stores the data in the video buffer 210. Then, the communication terminal 200 reads the video data from the video buffer 210 at a certain timing, and displays the video on the display 204.

[0004] By repeating the above operation, it becomes possible for the communication terminal 200 to display the moving image acquired by the video camera 105 at the communication terminal 100.
Here, the reason for storing the video data in the video buffer 210 is as follows. Packets on a network flow with fluctuations (jitter) over time for various reasons.
This is shown in FIG. As shown in FIG. 10, even if one frame of video data is transmitted at a constant interval T from the video data transmitting side, the video data is not always received at a constant interval T on the receiving side due to the influence of jitter. Absent. For this reason, the reception interval is widened as shown in part A of FIG. 10, or the reception interval is narrowed as shown in part B of FIG.

Therefore, if the received data is immediately displayed without passing through the video buffer 210, the motion of the video displayed on the display becomes slow (part A),
It becomes faster (part B). In order to prevent this, the video buffer 210 needs to be long enough to absorb the jitter.
In general, the effect of the jitter is reduced by reading the video at the same timing as when the video is acquired when the video is reproduced.

[0006]

However, in the above conventional example, a video camera 105 capable of externally controlling pan, tilt, and zoom is connected to the communication terminal 100, and the video camera 105 is connected to the video camera 105 for displaying images. 10
No consideration was given to the case of controlling the posture of No. 5. This will be specifically described. In the above-described conventional example, since the video data to be displayed is buffered, the difference between the time when the video is obtained and the time when the video is displayed becomes large. Therefore, when the user controls the video camera 105 such as panning, tilting, and zooming while watching the video from the communication terminal 200 that is displaying the video, the video after moving the video camera is displayed. It will take some time before. Therefore, there is a problem that the user further moves the video camera, and moves the video camera more than the user intended.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problem, and reduces a difference between a time obtained by a video transmitting terminal and a time at which a video display terminal displays a video image during remote operation of an imaging apparatus. A video communication system, an information processing device, and a control thereof that improve the ability to follow the operation state of a display image when operating the imaging device of the video transmission terminal while viewing the display image on the video display side terminal The aim is to provide a method.

[0008] Another object of the present invention is to provide a method for operating an imaging device in a video transmitting terminal from a video display terminal to quickly obtain an image acquired by the video transmitting terminal after operating the imaging device. In the video display terminal.

[0009]

A video communication system according to the present invention for achieving the above object has the following arrangement.
That is, a video communication system for receiving and displaying video information from at least one video transmission terminal on at least one video display terminal, wherein the video information from an imaging device provided in the video transmission terminal is displayed on the video display terminal. Receiving means for receiving at the terminal, buffer means for buffering the received video information, first display means for displaying an image based on the video information accumulated in the buffer means, and the video display terminal, Detecting means for detecting that the imaging device is in the controlled state, and detecting the video information received by the receiving means without passing through the buffer means when the detecting means detects that the imaging device is in the controlled state. And a second display means for displaying the information.

[0010] Further, there is provided a configuration under the information processing apparatus of the present invention which achieves the above object. That is, an information processing apparatus that receives and displays video information from an external device on a network, and includes a receiving unit that receives the video information, a buffer unit that buffers the received video information, and a buffer unit. First display means for displaying an image based on the accumulated video information, detection means for detecting that the imaging device acquiring the video information transmitted by the external device is in a controlled state, and the detection means And a second display means for displaying the video information received by the receiving means without passing through the buffer means, when it is detected that the imaging device is in the controlled state.

Preferably, in the above-mentioned configuration, the image processing apparatus further comprises an erasing means for erasing the video information stored in the buffer means when the detecting means detects that the imaging device is in a controlled state.

[0012] Furthermore, a control method of a video communication system according to the present invention for achieving the above object provides a video communication system in which at least one video display terminal receives and displays video information from at least one video transmission terminal. A control method, comprising: a receiving step of receiving video information from an imaging device provided in the video transmitting terminal at the video display terminal; a buffering step of buffering the received video information; A first display step of displaying an image based on the obtained video information; a detection step of detecting that the imaging device is in a controlled state in the video display terminal; And a second display step of displaying the video information received in the receiving step without passing through the buffering step when the state is detected. .

According to another aspect of the present invention, there is provided a method for controlling an information processing apparatus for receiving and displaying video information from an external device on a network, the method comprising: A receiving step of receiving, a buffering step of buffering the received video information, a first display step of displaying an image based on the video information accumulated by the buffering step, and a video information transmitted by the external device. A detecting step of detecting that the imaging device being acquired is in a controlled state; and, when detecting in the detecting step that the imaging device is in a controlled state, the video information received in the receiving step to the buffer. And a second display step of displaying without a step.

[0014]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a block diagram illustrating the configuration of a video communication system according to a first embodiment. Reference numerals 10 and 20 denote communication terminals, and the respective terminal bodies 11 and 21 have a CPU
1, 51, ROMs 42 and 52, RAMs 43 and 53, external storage devices 44 and 54, and the like. The communication terminals 10 and 20 are communicably connected by a network 30.

Reference numeral 12 denotes a video camera. Reference numeral 13 denotes a video input unit, which takes in a video analog signal output from the video camera 12 and digitizes it. 1
Reference numeral 4 denotes a camera control unit that controls pan, tilt, zoom, and the like of the video camera 12 (hereinafter, referred to as posture control). Reference numeral 15 denotes a network transmission / reception unit that transmits a packet to the network 30 and receives a packet flowing through the network 30. Each configuration of the video input unit 13, the camera control unit 14, and the network transmission / reception unit 15 includes hardware adapted to each configuration,
This is realized by the CPU 41 executing a control program stored in the ROM 42 or the RAM 43 and appropriately controlling these hardware.

Reference numeral 27 denotes a video buffer unit for storing received digital video data. Video buffer unit 27
Uses a RAM 53 or an external storage device 54 as a video buffer, and constitutes a FirstInFirstOut memory from which data stored first can be read first.
Reference numeral 22 denotes a display, which performs various displays under the control of the CPU 51. The received video is also displayed on this display 2.
2 is displayed. Reference numeral 28 denotes a mouse as a pointing device, and 29 denotes a keyboard.

Reference numeral 23 denotes a camera control unit which controls the video camera 1 designated by a mouse 28 or a keyboard 29.
The command such as a pan angle, a tilt angle, and a zoom value of No. 2 is converted into a command, and the command is transmitted to the network transmitting / receiving unit 24 for transmission to the communication terminal 10. Reference numeral 26 denotes a buffer suppression unit which instructs a video buffer unit 27 to buffer video data or to display the video data on a display as it is. Reference numeral 25 denotes a camera control detection unit which determines whether or not a camera control request has been made, and transmits the determination result to the buffer suppression unit 26. Reference numeral 24 denotes a network transmission / reception unit that transmits a packet to the network 30 and receives a packet flowing through the network 30.

The components indicated by the reference numerals 23 to 27 are hardware adapted to each configuration, and a CPU.
51 is realized by executing a control program stored in the ROM 52 or the RAM 53 and appropriately controlling these hardware.

FIG. 2 is a diagram showing a display example of the communication terminal 20 according to the present embodiment. In the figure, reference numeral 301 denotes a mouse cursor displayed on the display 22. As is well known, the mouse 28 causes the mouse cursor 301 to move to the mouse 2
8 can be moved freely. 30
Reference numeral 2 denotes an image displayed on the display 22 and the communication terminal 1
0 is an image from the video camera 12. Reference numeral 303 denotes a user interface for operating the camera.

Hereinafter, the operation until the video data is output from the communication terminal 10 will be described with reference to FIG.

The analog video data output from the video camera 15 of the communication terminal 10 is digitized by the video input unit 13. The digitized video data is packetized by the network transmission / reception unit 15 and transmitted to the communication terminal 10.
Is sent out to the network 30 at a predetermined cycle.

Next, the operation from the reception of the video data by the communication terminal 20 to the display thereof will be described with reference to FIGS. 1, 3 and 4. FIG. 3 is a block diagram showing in detail the configuration of the video buffer unit 27 and its peripheral parts according to the present embodiment. FIG. 4 is a flowchart showing a procedure for displaying received video data by the communication terminal 20 of the present embodiment.

As shown in FIG. 3, the video buffer unit 27 includes a buffer memory 27a, a buffer control unit 27b, and an output control unit 27c. The buffer memory 27a is configured using, for example, a part of the RAM 53, and in this example, a maximum of 1
It is assumed that video data for zero screen can be stored. Also,
The buffer control unit 27b buffers the input video data in the buffer memory 27a when the suppression signal of the buffer suppression unit 26 is off, and sends the input video data to the output control unit 27c when the suppression signal is on. . When the suppression signal is off, the output control unit 27c
The buffered data is read from 7a and output to the drawing unit 55, and when the suppression signal image is on, the video data from the video buffer unit 27b is output to the drawing unit 55. As a result, when the suppression signal is ON, the input video data is not stored in the buffer memory 27a but is output to the drawing unit 55 as it is.

The drawing unit 55 draws an image on the VRAM 56 based on the input video data. VRAM5
The image drawn on 6 is displayed on the display 22 by a video controller (not shown).

The operation of the buffer suppressing section 26 and the video buffer section 27 described above will be further described with reference to the flowchart of FIG.

First, in step S11, it is determined whether a packet of video data has been received. If the packet has been received, the process proceeds to step S12, and it is determined whether the camera is currently being controlled. This determination is made by checking whether the suppression signal from the camera suppression unit 26 is on as described above. If the camera is not currently being controlled, the process proceeds to step S13, where the video data is buffered in the buffer memory 27a.

In step S14, it is determined whether or not video data for 10 screens has been stored in the buffer memory 27a, or whether or not the display flag is on. When the video data for 10 screens is buffered, the display flag is turned on to start the display at a predetermined display timing (step S15). Then, at the display timing, the oldest one-frame video data is read from the buffer memory and drawn on the display 22 (steps S16 and S17). The read video data is deleted from the buffer memory 27a. Thereafter, while the display flag is on, buffering of the received video data in the buffer memory 27a and buffer memory 27a
The display of the video data read from a is performed in parallel. Then, when there is no more video data from the buffer memory 27a, the display flag is turned off (step S18,
S19).

When a camera control request is issued from the camera control request unit 23 during the above-described processing, the camera control detection unit 25 detects the request and transmits it to the buffer suppression unit 26. When the buffer suppression unit 26 turns off the suppression signal, the buffer control unit 27b passes the input video data to the buffer output unit 27c without passing through the buffer memory 27a. Then, the buffer output unit 27c sends the video data to the drawing unit 55, so that the video data received without buffering is displayed (Step S).
12, S20).

With the above configuration, the video data is not buffered when the camera is operated.
The video changed by the camera operation can be displayed with a short delay time. Therefore, there is an advantage that the camera operation can be easily performed.

In the above description, a one-to-one communication system has been described as an example. However, the present invention is not limited to this, and it is apparent that the present invention can be applied to a many-to-many communication system. The communication terminal of this embodiment is dedicated to transmission (communication terminal 10) and display only (communication terminal 29).
However, the present invention is not limited to this, and can be applied to a case of mutual communication.

As described above, according to the first embodiment, when the camera is operated from the apparatus on the image display side, the image after the camera is moved is displayed without buffering. The difference between the time and the display time can be shortened, and the operability of the camera is improved.

<Second Embodiment> In the first embodiment, if video data is already stored in the video buffer unit 27 at the time of camera operation, the buffered video data is stored after the camera operation is completed. The latest video cannot be displayed until all are read. The second embodiment is to solve this problem.

FIG. 5 is a block diagram showing the configuration of the video communication system according to the second embodiment. In the figure, the same components as those of the first embodiment (FIG. 1) are denoted by the same reference numerals, and a detailed description thereof will be omitted. Reference numeral 61 denotes a buffer erasing unit, and when the camera control detecting unit 25 detects a user's camera operation, the video buffer unit 2
The video data buffered in 7 is deleted.

FIG. 6 is a block diagram showing in detail the configuration of the video buffer unit 27 and its peripheral parts according to the second embodiment. In the figure, the same components as those of the first embodiment (FIG. 3) are denoted by the same reference numerals. In the second embodiment, the buffer control unit 61 performs batch erasure of video data stored in the buffer memory 27a.

In the above configuration, the communication terminal 20
By moving the mouse cursor 301 on the display using the mouse 28, the camera control interface 30
When the operation of the video camera 12 is performed using the camera 3, the information is transmitted to the camera control request unit 23. Camera control request unit 2
3 converts the request into a command,
Pass to 4. The network transmitting / receiving unit 24 packetizes the command and transmits the packet to the network 30. Communication terminal 10
When the network transmitting / receiving unit 15 receives the packet,
The packet is returned to the command, which is passed to the camera control unit 14. The camera control unit 14 controls the camera according to the command.

FIG. 7 is a flowchart for explaining the processing procedure of the buffer erasing unit according to the second embodiment. When the camera control request is transmitted to the camera control request unit 23 of the communication terminal 20, the camera control detection unit 25 detects it. When detecting the camera control request, the camera control detection unit 25 notifies the buffer deletion unit 61 of the detection. Upon receiving this notification, the buffer erasing unit 612 checks whether video data is stored in the buffer memory 27a in the video buffer unit 27 (Steps S101 and S102). If video data has been stored in the buffer memory 27a, all video data stored in the buffer memory 27b is deleted (step S103).

With the above arrangement, the buffered video data is not displayed at the time of operating the camera, the video changed as a result of the camera operation can be displayed immediately, and the camera operation can be easily performed. There are advantages.

In the second embodiment, a one-to-one communication system has been described as an example. However, it is apparent that the present invention can be applied to a many-to-many communication system. Also, the communication terminal according to the present embodiment is divided into transmission only (communication terminal 10) and display only (communication terminal 20).
The present invention is not limited to this, and can be applied to a case of mutual communication.

As described above, according to the second embodiment,
In addition to the effects of the first embodiment, after the camera operation ends,
It is possible to quickly display video data in a new posture.

In the first and second embodiments,
When a control instruction for a camera is issued in the communication terminal on the video display side, the control instruction is detected in the terminal on the video display side to suppress the buffer. However, when the video camera 12 receives the control instruction, the terminal on the video transmission side adds information indicating the fact to the video data and transmits the video data, and the terminal on the video display side transmits the information based on the additional information of the video data. Alternatively, it may be recognized that the camera is under control. In this case, for example, the camera control detection unit 25
Separates additional information from the received video data packet and detects whether or not camera control is being performed. With this configuration, when there are a plurality of communication terminals on the image display side, it is possible to display an image that follows the operation of the camera, even if the communication terminal is placed on a display terminal that does not issue the instruction.

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU) of the system or the apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the above-described flowcharts. Each module shown will be stored in a storage medium. That is, for example, a “reception processing module”, a “buffer processing module”,
The program code of each of the “first display processing module”, “detection processing module”, and “second display processing module” is stored in a storage medium. Preferably, a program code of each module of the “erase processing module” is stored.

Here, each of the processing modules constitutes a control program for receiving and displaying video information from an external device on the network, and the reception processing module executes a reception process for receiving video information. . Also,
The buffer processing module implements buffer processing for buffering received video information. Further, the first display processing module implements a first display processing for displaying an image based on the video information accumulated by the buffer processing. The detection processing module implements a detection process of detecting that the imaging device that has acquired the video information transmitted from the external device is in a controlled state. The second display processing module, when detecting that the imaging device is in the controlled state in the detection processing, directly displays the video information received in the reception processing without going through a buffer processing. Implement the processing. Further, the erasure processing module implements an erasure process of erasing the video information accumulated by the buffer process when the detection process detects that the imaging device is in the controlled state.

[0049]

As described above, according to the present invention,
During remote operation of the imaging device, it is possible to reduce the difference between the time obtained by the video transmitting terminal and the time at which the video displaying terminal displays video, and the video transmitting terminal The followability to the operation state of the displayed image when the camera operation is performed is improved.

Further, according to the present invention, the video data in the buffer is deleted when the video display side terminal operates the imaging device in the video transmission side terminal, so that the video transmission side terminal is operated after the imaging device is operated. Can be displayed on the video display side terminal more quickly.

[0051]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a video communication system according to a first embodiment.

FIG. 2 is a diagram illustrating a display example of the communication terminal 20 according to the embodiment.

FIG. 3 is a block diagram showing in detail a configuration of a video buffer unit 27 and peripheral parts thereof according to the embodiment;

FIG. 4 is a flowchart showing a procedure for displaying received video data by the communication terminal 20 of the embodiment.

FIG. 5 is a block diagram illustrating a configuration of a video communication system according to a second embodiment.

FIG. 6 is a block diagram showing in detail a configuration of a video buffer unit 27 and peripheral parts according to a second embodiment.

FIG. 7 is a flowchart illustrating a processing procedure of a buffer erasing unit according to the second embodiment.

FIG. 8 is a diagram showing an outline of a general video communication system.

FIG. 9 is a block diagram illustrating a schematic configuration of a general video communication system.

FIG. 10 is a diagram for explaining occurrence of jitter in communication on a network.

FIG. 11 is a diagram showing an example of a memory map of a storage medium storing a control program according to the present invention.

[Explanation of symbols]

 10, 20 Communication terminal 11, 21 Terminal body 12 Video camera 13 Video input unit 14 Camera control unit 15, 24 Network transmission / reception unit 22 Display 23 Camera control request unit 25 Camera control detection unit 26 Buffer control unit 27 Video buffer unit 41, 51 CPU 42, 52 ROM 43, 53 RAM 44, 54 External storage device

Claims (13)

[Claims] 1. A video communication system in which video information from at least one video transmission terminal is received and displayed by at least one video display terminal, wherein video information from an imaging device provided in the video transmission terminal is received. Receiving means for receiving at the video display terminal; buffer means for buffering the received video information; first display means for displaying an image based on the video information accumulated in the buffer means; A detecting unit that detects that the imaging device is in a controlled state; and a buffer unit that, when the detecting unit detects that the imaging device is in a controlled state, the video information received by the receiving unit. And a second display means for displaying without passing through the video communication system. 2. The video display terminal, further comprising: an operation unit for controlling the imaging device; and a transmission unit for transmitting an operation content instructed by the operation unit to the video transmission terminal. The video communication system according to claim 1, wherein detecting that the imaging device is in a controlled state based on whether an operation is instructed by the operation unit. 3. The video transmitting terminal further includes a transmitting unit that adds additional information as to whether or not the imaging device is being operated to the video information and transmits the video information, and wherein the detecting unit receives the additional information. The video communication system according to claim 1, wherein the video communication system detects that the imaging device is in a controlled state based on the control information. 4. The image processing apparatus according to claim 1, further comprising an erasing means for erasing the video information stored in said buffer means when said detecting means detects that said imaging device is in a controlled state. The video communication system according to claim 1. 5. An information processing apparatus for receiving and displaying video information from an external device on a network, comprising: a receiving unit that receives the video information; a buffer unit that buffers the received video information; First display means for displaying an image based on the video information accumulated in the buffer means, and detection means for detecting that the imaging device acquiring the video information transmitted by the external device is in a controlled state; A second display unit for displaying the video information received by the reception unit without passing through the buffer unit when the detection unit detects that the imaging device is in the controlled state. Processing equipment. 6. An operation unit for controlling the image pickup apparatus, and a transmission unit for transmitting operation contents instructed by the operation unit to the external device, wherein the detection unit is operated by the operation unit. The information processing apparatus according to claim 5, wherein the information processing apparatus detects that the imaging apparatus is in a controlled state based on whether or not an instruction has been given. 7. The receiving means receives video information to which additional information as to whether or not the imaging device is being operated is added, and the detecting means adds the additional information extracted from the received video information to the additional information. The information processing apparatus according to claim 5, wherein the information processing apparatus detects that the imaging apparatus is in a controlled state based on the information. 8. The image processing apparatus according to claim 5, further comprising an erasing means for erasing the video information stored in said buffer means when said detecting means detects that said imaging apparatus is in a controlled state. An information processing apparatus according to claim 1. 9. A control method for a video communication system in which video information from at least one video transmission terminal is received and displayed by at least one video display terminal, wherein the video information is transmitted from an imaging device provided in the video transmission terminal. A receiving step of receiving video information at the video display terminal; a buffering step of buffering the received video information; a first display step of displaying an image based on the video information accumulated by the buffering step; In the video display terminal, a detecting step of detecting that the imaging device is in a controlled state, and, when detecting that the imaging device is in a controlled state in the detecting step, the video information received in the receiving step A second display step of displaying without going through the buffering step. 10. A method for controlling an information processing apparatus for receiving and displaying video information from an external device on a network, comprising: a receiving step of receiving the video information; and a buffering step of buffering the received video information. A first display step of displaying an image based on the video information accumulated by the buffering step; and a detection step of detecting that the imaging device acquiring the video information transmitted by the external device is in a controlled state. And a second display step of displaying the video information received in the receiving step without passing through the buffering step when the imaging device detects that the imaging device is in the controlled state in the detecting step. And control method. 11. The image processing apparatus according to claim 10, further comprising an erasing step of erasing the video information accumulated by said buffering step when said detecting step detects that said imaging device is in a controlled state. The control method described in 1. 12. A computer-readable memory storing a control program for receiving and displaying video information from an external device on a network, wherein the control program causes a computer to receive the video information. Buffer means for buffering the received video information; first display means for displaying an image based on the video information stored in the buffer means; and an imaging device for acquiring video information transmitted by the external device Detecting means for detecting that the imaging apparatus is in the controlled state, and displaying the video information received by the receiving means without passing through the buffer means when the detecting means detects that the imaging device is in the controlled state. A computer readable memory functioning as second display means for performing the operation. 13. The control program functions as the erasing means for erasing video information stored in the buffer means when the detecting means detects that the imaging device is in a controlled state. 13. The computer readable memory according to claim 12, further comprising a control program for causing the computer to execute the control program.